The intermittent fasting diet plan alternatives eating with fasting and is said to improve weight loss and heart health, but it may not be safe for everyone.
The intermittent fasting diet plan, or IF, is a diet that alternates “feed periods” of eating normally with “fast periods” of not eating at all. It is often used as a way to lose weight and build muscle.
Types of intermittent fasting weight loss
There are a variety of ways to structure a intermittent fasting diet plan.
One popular method is alternate day fasting. This diet switches between days of eating and snacking as normal, or feed days, and days when you consume no food, or fast days. Fast days can also be days when you eat a very small amount of food, such as 300 to 500 calories, or when you consume only liquids, such as milks or juices.
Another form of the intermittent fasting diet is time-restricted feeding. In this type of diet, you eat a normal amount of food every day but restrict your feed period, for example from 8 a.m. to 4 p.m., and fast for the remaining hours of the night and day. A split of 16 fast hours and 8 feed hours is common, though feed periods can range from 4 to 10 hours.
Other common intermittent fasting diet plans include the 5:2 diet, or fasting for two days out of the week, and the Eat-Stop-Eat diet, which involves fasting from dinner one night to dinner the next night once or twice per week.
Why does intermittent fasting weight loss work?
After eating, you have readily available energy from the fats, sugars, and proteins that you just consumed. During periods of fasting, however, you no longer have calories to use from a recent meal. As a result, your body is more likely to burn stored fat for energy.
An intermittent fasting diet is intended to create recurring fast periods that promote efficient energy use and muscle building. However, according to a review published in the American Journal of Clinical Nutrition, evidence about the safety of intermittent fasting is mixed, indicating that it can pose both benefits and risks to your health.
Benefits of intermittent fasting weight loss
Several animal studies of IF have found that it promotes a longer lifespan. There have been some claims that intermittent fasting weight loss results in increased longevity for humans as well, particularly when it is used to maintain a healthy weight rather than as a weight-loss tool. However, the ethical and practical difficulties of creating a study long-lasting enough to examine the effect of intermittent fasting on human lifespan have prevented these claims from being fully verified.
What has been verified is that intermittent fasting can be a helpful strategy for losing weight and building muscle.
A 2014 study found that IF was as effective as calorie restriction when it came to weight loss, resulting in a loss of 3 to 8 percent of body weight from fat over a period of 3 to 24 weeks. The study also showed that fasting benefitted participants’ heart health, as well as reducing risk factors for type 2 diabetes, such as insulin resistance.
Other studies have found that intermittent fasting may lower cholesterol levels, reduce oxidative stress, and limit participants’ risk of heart diseases such as coronary artery disease. (Most studies note that these benefits are more likely to occur when fasting is combined with a healthy diet and exercise.)
Dangers of intermittent fasting diet plan
The news about intermittent fasting is not all as positive or straightforward as it may first appear.
A literature review in the journal Nature noted that nearly all studies that found that IF improves heart health involved obese participants. Very few studies have yet been done on how such dieting affects heart health in normal-weight or overweight people.
Many articles on fasting note that it can be dangerous for certain groups of people, regardless of its potential health benefits. This includes children, the elderly, and women who are pregnant or breastfeeding.
Fasting can also result in unhealthy eating patterns. An article in the Canadian Medical Association Journal noted that intermittent fasting may encourage bingeing, or consuming excessive and unhealthy calories, during feed periods due to the assumption that unhealthy eating is offset by fast periods.
Additionally, men have been the primary subjects in most clinical trials on fasting. There is less data about how IF affects women. Some studies that have been done with women found that women show decreased glucose tolerance and no change in their insulin sensitivity, indicating that IF may be unhealthy for women’s metabolisms.
More research is necessary to know exactly who can benefit from intermittent fasting and how it can affect your health. Until then, it’s important to talk with your doctor before beginning any diet or fasting regimen.
August 11, 2017
Janet O’Dell, RN